Chmod 700 Explained — Securing ~/.ssh, Home Directories & Root Backups

Chmod 700 Permissions

Chmod 700: Chmod 700 gives the owner total Read, Write, and Directory Traversal (Execute) rights (7), while barring Group and Others entirely (00). Represented symbolically as rwx------, it is the standard for private user directories like ~/.ssh, root administrative scripts, and encrypted personal storage vaults.

Class	Read (4)	Write (2)	Execute (1)	Sum
Owner (User)	✓	✓	✓	7
Group	—	—	—	0
Others (Public)	—	—	—	0

Class

Read (4)

Write (2)

Execute (1)

Sum

Owner (User)

✓

Group

—

Others (Public)

—

Technical Deep-Dive: Chmod 700 (drwx------)

Bitwise binary arithmetic, POSIX DAC rules, and security guidelines for production servers.

1. Binary Calculation Mechanics

POSIX file systems represent permissions in triplets of binary bits where Read is 4 (2^2), Write is 2 (2^1), and Execute is 1 (2^0). In chmod 700, each digit computes as:

• Owner: 7 (Read Write Exec)
• Group: 0 ()
• Others: 0 ()

2. Practical CLI Execution

Apply this configuration to files or directories with the standard Linux terminal commands:

# Apply to specific target:

chmod 700 ~/.ssh

# Apply recursively to subdirectories:

chmod -R 700 ~/.ssh

Frequently Asked Questions

Why does the ~/.ssh directory require chmod 700?

If the ~/.ssh directory is readable or writable by other users, an unauthorized account could read your known_hosts, inspect your public keys, or plant an unauthorized authorized_keys file. OpenSSH blocks connections if ~/.ssh has permissions looser than 700.

Can other users see filenames inside a chmod 700 directory?

No. Because Read and Execute are 0 for Group and Others, unprivileged users cannot run 'ls' inside the directory or 'cd' into it, ensuring complete file enumeration privacy.

Does root obey chmod 700?

The Linux root superuser (UID 0) bypasses standard Discretionary Access Controls and can access chmod 700 directories unless restricted by mandatory access frameworks like SELinux or AppArmor.